The present invention relates to the preparation of a dehydrated pre-cooked rice product which may be rapidly rehydrated and cooked for consumption.
Dehydrated rice products have been prepared conventionally by soaking raw rice followed by water cooking, or by steaming the soaked rice, or by a combination of water cooking and steaming for cooking the rice and then subsequently drying the cooked rice. A problem which has been persistent in the art to prepare a dehydrated pre-cooked rice product which can be prepared in a short period of time for consumption is the ability to hydrate and gelatinize the rice uniformly so that the dehydrated pre-cooked rice, upon cooking and reconstitution for serving, has a uniform consistency of texture. In addition, water cooking requires significant amounts of energy input because of the amount of water utilized which, generally, is on the order of a ratio of water to rice by weight of at least about 5:1 and usually on the order of about 10:1.
When soaked or water-cooked rice subsequently is steam cooked, conventionally, the rice is steam cooked at substantially atmospheric pressure. However, British Patent Specification 563,792, which proposes steeping rice in water and then steaming it at atmospheric pressure, mentions that prior unidentified processes for the treatment of rice had been proposed wherein rice was steeped in water and subsequently steamed at a pressure above atmospheric pressure to gelatinize it.
U.S. Pat. No. 3,086,867 discloses a process for preparing a quick cooking dehydrated brown rice product which is said to be gelatinized uniformly wherein raw brown rice is hydrated in water at a temperature of from about 75.degree. C. to 100.degree. C. to increase the moisture content of the rice to from 20% to 50% to split the bran coat partially. The hydrated rice then alternately is steamed at a temperature of 100.degree. C. or greater, which is for gelatinizing the rice, and sprayed with water, which is for increasing the moisture content of the rice about 3% to 5% during each addition of water, until the rice is completely gelatinized and has a moisture content above 65%. The cooked rice then is dried in a manner in which moisture is removed from the surface of the rice faster than water can diffuse from the interior of the rice to the surface of the rice grain so the rice will be puffed and porous.
U.S. Pat. No. 4,338,344 discloses a method for preparing a quick-rehydrating, fully gelatinized rice in which raw rice is introduced into and advanced through a water bath contained inside an inclined, enclosed chamber that the water will cover from about between 40% and 90% of the length of travel of the rice through the chamber. The water is maintained at a temperature of from about 80.degree. C. to 110.degree. C. The rice is conveyed with agitation from the bottom of the water bath to the surface of the water under atmospheric conditions at a temperature up to 100.degree. C. within a time range of from 10 to 50 minutes. When the rice exits the surface of the water bath, the partially cooked rice enters a steam atmosphere, which is disclosed to be preferably under pressure. For superatmospheric operation, the temperature of the water bath is from about 100.degree. C. to 110.degree. C. and the cooking time of the rice in the water bath is from about 2 to 30 minutes. When the partially cooked rice is steamed under pressure, pressures on the order of from of 150 mm Hg to 260 mm Hg above atmospheric pressure are said to be preferred. The rice leaving the water bath is conveyed with agitation through the steam atmosphere for from 1 min to 30 mins after which it is removed from the chamber and dried.